The present invention relates to latches and levers, specifically ejector latches and ejector levers which may be adapted for use to secure and release computer-type boards in racks and cabinets, such as large boards known as peripheral component interconnect (PCI) boards. These boards are used to hold such electronic components as processor circuits, banks of switches, banks of transducers, transformers and other components and modules. Such PCI boards are generally larger than PC boards (personal computer boards) and can be generally square or rectangular in shape; and are generally sized from six (6) inch to ten (10) inches on a side. Compared to the much larger boards, previously used in the computer, the switching circuit, and the telecommunications industries, these boards have become known as compact PCI boards. It important to be able to easily insert such a module carrying PCI board with a positive snap-in connection and positive snap-out release. Moreover, it is important to have an insertion aid and/or a pull-out aid, such as a handle or a hold. This snap-in and snap-out operation has been implemented with ejector latches.
However, these latches must also comply with the general industry standards for this type of latch, including the standards for mounting on a faceplate on the front of a board, and the engagement with the chassis mounted flange, which acts as combination guide block and keeper. These standards are defined as a subset of IEEE1101.1 and IEEE1101.10 specifications known as Compact PCI (PICMG 2.0) standards. Many inject/eject latches are in the marketplace and meet these standards. Examples are those sold by manufacturers such as Rittal, Schroff, Elma and Bivar. As manufactures are using higher frequency circuits on compact PCI boards, electromagnetic compatibility (EMC) is becoming an increasing concern. The existing prior art ejector latch configuration requires a large cutout in the aluminum faceplate normally mounted to the outside edge of a compact PCI board. This large cutout often is a source of electromagnetic radiation. Furthermore, such prior art compact PCI board latches often do not have a low profile and generally have a limited degree of movement and mechanical leverage.
FIG. 1 shows a typical example of a prior art compact PCI board 21 with a pair of prior art inject/eject latches 23 mounted on its outboard edge faceplate 25. Chassis connectors 27 have wire leads 29 into the board 21. Each latch 23 includes a base/alignment pin block 31 that carries a larger leading guide pin 33 and a smaller seating guide pin 35.
FIG. 2 shows a perspective side view of the prior art pin 33 of FIG. 1 showing the single structure combination housing 37 having a claw-shaped end pawl 37a and a thumb handle 37b. The base/alignment pin block 31 is a casting with a number of openings and shoulders. A spring biased release button 39 is shown in FIG. 3, which is a longitudinal cross-sectional view of FIG. 2 taken as shown in FIG. 2. The spring 41 biases the thumb release button away from the pawl 37a to have a projection shoulder 39a extend through the opening in the back of the housing 37 to prohibit the rotation thereof and to keep the pawl 37a locked in position.
This prior art device has a high profile and its faceplate mounting with relatively large cutout results in a relatively large amount of EMF signal leakage (electromagnetic frequency radiation).
The IEEE Compact PCI specification defines the location, with respect to a chassis, of the faceplate in its fully inserted and fully extracted positions, where fully extracted is defined as being loose for removal. It also defines the area of the chassis to which a latch is to interact when inserting and extracting (ejecting) a board.
An object of this invention is to meet these IEEE requirements for a latch for Compact PCI board installations, which allows for more efficient EMC shielding.
A second object of this invention is to provide a latch that needs a smaller cutout in the PCI board faceplate.
An third object of this invention is to provide such a latch that has a low profile when folded closed.
A further object of this invention is to provide such a latch with a greater degree of rotation and a two-phase operation.
An even further object of this invention is to implement such a two-phase operation by having the ejector successively operating first in a rotary motion and then secondly in a linear motion.